The main object of the next generation cellular communication system is to improve the system throughput, and MIMO (Multiple-Input-Multiple-Output, multiple-input-multiple-output) is an important technical solution to achieve the object in modern mobile communications. The technology of Large-scale antennas is further development of the MIMO technique, which improves the system throughput by deploying massive antennas at the base station side, as shown in FIG. 1.
In an MIMO system, the base station is required to transmit pilot signals to the whole cell at intervals, a UE (user equipment) in the cell performs the channel measurement through the pilot signals, which is used to calculate channel parameters such as CQI (channel status information) and to feed back the channel parameters to the base station. In the conventional MIMO technology, there are few transmitting antennas (generally no more than 8 antennas), thus each of the antennas transmits orthogonal pilot signals. However, in an MIMO system with large-scale antennas, with the increase of antennas, massive orthogonal pilot signals occupy a lot of time-frequency resources and reduce the actual system throughput. In view of this, the following method is provided in conventional technology.
The transmitting antennas are divided into multiple groups, the antennas in one transmit a same pilot signal, and the antennas in different groups transmit orthogonal pilot signals, i.e., the antennas in different groups transmit the pilot signals in a frequency-division mode. In the method, the same pilot signal is transmitted on the antennas in one group, which may save pilot overhead caused by multiple antennas, but the receiving end of the pilot signal cannot perform a complete channel measurement.